Abstract:

A novel adsorbent of covalently bounded quaternary ammonium activated carbon (CQA) was prepared by silylation reaction with both organosilicon quaternary ammonium salt (QA) and activated carbon (AC) as raw materials. The CQA was characterized by FTIR, SEM and BET. The results showed that QA was successfully loaded on the surface of AC by covalent binding, and had an important influence on the morphology and structure of AC. The nitrate and phosphate adsorption capacities for CQA were greatly improved. The adsorption behaviors of nitrate and phosphate from aqueous solutions on CQA were investigated using batch experiments. The kinetics study revealed that adsorption of nitrate and phosphate onto CQA followed the pseudo-second-order kinetic model, indicating that the adsorption process was mainly controlled by the chemisorptions. The adsorption data fitted Langmuir and Freundlich isotherm models well, and the maximum nitrate and phosphate adsorption capacities for CQA were 14.829 and 8.442 mg/g, respectively. The effects of pH on the adsorption of nitrate and phosphate were also investigated. The results showed that when pH was from 4 to 9, it was suitable for simultaneous removal of nitrate and phosphate from aqueous solution by CQA.

Key words: activated carbon, nitrate, phosphate, modification, adsorption

摘要：

以有机硅季铵盐和活性炭为原料, 利用硅烷化反应, 制备一种新型吸附材料——共价键型季铵化活性炭(CQA)。通过FTIR, SEM和 BET对CQA进行表征, 验证季铵盐能够通过共价键结合, 成功地负载到活性炭表面, 并对活性炭的形貌结构产生重要影响。CQA对硝氮和磷酸盐的吸附能力都大大提高, 对含硝氮和磷酸盐的溶液的吸附实验表明: CQA对硝氮和磷酸盐的吸附机理均符合拟二级反应模型, 说明吸附过程主要由化学吸附控制; 吸附过程可以用Langmuir和Freundlich等温吸附模型较好地进行描述,最大吸附容量分别为14.829和8.442mg/g。最后考察pH对硝氮和磷酸盐吸附行为的影响, 结果表明, 当pH为4~9时, 比较适宜CQA对硝氮和磷酸盐同时去除。

关键词: 活性炭, 硝氮, 磷酸盐, 改性, 吸附